Technical Field
The present invention relates to an aluminum alloy brazing sheet for heat exchangers used for an automotive heat exchanger, etc.
Description of the Related Art
Generally, as a tube material in an automotive heat exchanger such as an evaporator or a condenser, an aluminum alloy brazing sheet obtained by cladding a core with a sacrificial material and a brazing filler metal (hereinafter sometimes referred to as a brazing sheet) formed into a tube by electric resistance welding has been used. In such a brazing sheet for use as a tube material, an Al—Mn-based alloy, for example, is used as the core, and an Al—Zn-based alloy, for example, is used as the sacrificial material on the inner side, which in one side of the core, i.e., the side that is constantly in contact with a refrigerant. Further, when formed into a tube, an Al—Si-based alloy is usually used as the brazing filler metal on the outer side, which is the other side of the core.
In recent years, there is a trend toward lighter and smaller automotive heat exchangers. With this trend, the thinning of a tube material, which occupies a large part of the mass of a heat exchanger, has been desired. For the thinning of a tube material, it is necessary to increase strength and corrosion resistance corresponding to the decrease in thickness. In response to such needs, aluminum alloy brazing sheets and clad materials for achieving high strength, high corrosion resistance, etc., have been proposed.
For example, JP-A-2001-170793 discloses a high-strength aluminum alloy clad material for heat exchangers having excellent high frequency weldability and corrosion resistance, characterized in that a core and a sacrificial material are each specified to have a predetermined alloy composition, the matrix of the core has a fiber structure, and the clad material has a tensile strength of 170 to 260 MPa.